Circuit interrupters



March 12, 1957 v. cHiABALA 2,785,345

CIRCUIT INTERRUPTERS Filed Nov. 27, 1953 2 Sheets-Sheet l Fig.|.

WITNESSESI INVENTOR /.Wy Leonard v Chobolo.

@WAN/Umain March 12, 1957 l.. v. CHABALA 2,785,345

CIRCUIT INTERRUPTERS Filed NOV. 27, 1953 Fig.3.

Rated Trip Current o Trip Current 2 Sheets-Sheet 2 VFig..4.

Normal Operating Temp.

Temperature 0 Temp. Drop from Operating Level.

Time

@7:35345 -cnzcnlr INTERRUPTERS Leonard yV. Chabala, Pittsburgh,-Pa.,assigner to Westinghouse Electric CorporatiomfE'ast Pittsburgh, Pa.,.a

corporation of Pennsylvania .My invention relates generally to circuitinterrupters, 4and it has .reference r in 'particularto Vautomaticreclosing circuit breakers. r

Generally stated, it isran object of my invention to provide forincreasing the current rating of a reclosing circuit breaker when it hasbeen open for a predetermined tirne, to permit it to handle increasedcurrents upon reclosing, such as may be due-to loss of diversity ofdemand on the system.

lMore specifically, it is an object of my inventionto provide forchanging the effective ampere turns of the operating coil of arecloserwhen the recloser is reclosed after-it has been A'open'for apredeterminedtirne.

/`Another object of my invention is to provide for decreasing theeffective `ampere 'turns of the operating coil of a recloser when itopens, and formaintaining such decreasedcondition when the recloserrecloses, only if 'the recloser remains open for a predetermined time.

Yet another objectof my invention is to provide for shunting a portionof the .ampere turns of the operating coil of Va re'closer whenit opens,and using a thermal latch for maintaining said shunted conditionif thetemperature of the recloser falls below al predetermined level.

It is an important object of my invention to provide vfor shunting'theseries operatingrcoil'of a reclosing circuit breaker when it lockslopen,vand f'orutilizing a latch having a bimetallicmember responsive tothe temperature of the oil to maintaihrrsuch shunt in the eventthat thebreaker remains open for a Asuliicientftime foruthe `temperaturethereoffuto drop to a predetermined value.

Other objects will in .part be obvious, and will-in part be explainedhereinafter.

-In' practicing my. invention in accordance with oney ofitsembodime'nts, an auxiliaryswitch is disposed to -be .actuated vfromthe lockoutstoggle linkage of a reclosing vcircuit .breaker to `connectaJresistor in shunt withthe solenoid coil of the .breaker to increaseits effective trip rating. `So as Ito'enable .the breaker to attain thisincreased rating when .reclosed-after arelatively long delay oftwentyminutes orso, .a bimetallic latch is provided that becomes effectiveonly .when the breaker is open -for a .relatively longinterval,.otherwise the switch opens and-removes the shunt vvwhen therecloser is reclosed.

vFor a more complete understanding of the nature and scope of myinvention, reference may be made tothe yfollowing description which maybe read in connection with the :drawings inwh'ich:

:Fig l.is..arsubstantially central vertical sectionfview of `a circuitbreakeremb'odyingthe invention .in one of its forms; v:Fig l2 is an,enlarged vertical sectional view in part of the vbreakcrshown in 'Fig.1 taken to the .rear of the counter and atan angle to Athe section ofFig. 1;y

Fig. :3 is a .characteristic temperature-current Acurve .for the breakershownyin-Fig. 1; and

`Fig. 4 is a characteristic -time-temperature .curve :for

, the same; breaker.

United States Patent ICC issubstantially the same as that described ,inPatent No.

2,622,167 of H. L. Rawlins etal. except that the dash- .erably a liquidhaving arc extinguishing ability suchras oil, Therupper end of tank 2 isprovided with an out- `vvardlyextending flange 4 on which the flange 8of a cover casting -6 is adapted to be seated, preferably, Awith agasket 1 9 interposed therebetween. Cover casting 6 may be secured tothe tank in any desired manner, such for example, as by bolts (notshown) secured torsuitably formed brackets on the tank.

The breaker contacts and certain of the contactactuating mechanismareadapted to be supportedin tank 2 from cover casting 6 by means of a pairof inte/gral supporting lugs 16 (only one of which is shown) dependingfrom the top wall of the cover casting and adapted to engage insulatingspacer rods 18 having threaded studs (not shown) engaging threadedopenings in the rods, lugs 16 and a supporting casting 2i). A supportingplate 22. may be supported in a similar manner from casting 2li, so thata solenoid coil 24 may be mountedtbetweren casting 2) -and supportingplate 22, whichact 'as pole pieces with thevcentral opening in the coilaligned with openings provided in casting 20 and plate 22.

:Spaced stationary contacts 26 ofthe breaker are each ysupported fromplate 22 by a support tube 28 of insulating material, such ,astiben withthe stationary con- Ytacts being mounted on support 2S, by means ofscrews 3Q Aand with the upper end vof thesupport 28 having brackets32Ybly means of which the support is securedto supporting plate 22.

vlimited pivotal movement about atransverse axis on con- `tact actuatingrod 44. Contact rold744 should be of an insulating material such as beror a molded insulating material.

The upper end ofgcontact actuating rod 44 has apair of connecting links46 positioned one at each side thereof `and pivoted thereon as by apivot pin 48, with the upper ends of these connecting links mounted ony,a `V` common pivot pin Stifor a pair of toggle levers 5,2 and 54.Toggle leverswSNZ and 54 are both formed of sheetmaterial, with lever54being bent tosubstantially'channel form with outwardly extendingflanges 56 adapted to be received at the free ends thereof in recessesS8 provided inuthe Vspaced downwardly depending fingers of yan angledsupporting bracket 60 which, `in turn, is secured to a lug 62 integralwith the coverfcasting. Preferably, v the base of the channel part oftoggle lever 54 isgextended at 66 through the space between thesupporting lingers of vbracket 69, 4and the other end oflever 54 thesides .of the channel formation thereof areextendedto be mounted onpivot pin 50. Lever 52 has avhooked extension 69 extending through lever:5,4 to limitseparation therefrom. A coil tension spring 68 has oneeudhookedrinto an opening provided in toggle lever 5.2, and has theopposite end thereofhooked over a spring support on the cover casting. Yi

Solenoid coil 24 previously mentioned is adapted to be opening thecircuit .breaker-contacts. The central open- 3 ing through coil 24preferably is provided with a cylindrical sleeve 74 in which a solenoidcore 76 is adapted to be slidablyV mounted in a piston-like manner. Thesleeve 74 communicates with an annular passage 73 in the casting, whichconnects with a passage Sti having a threaded end opening 81 forreceiving a plug (not shown) if all time delay operation of the breakeris desired.

. A contact actuating sleeve S2 is telescoped over contact actuating rod44 and its lower end is received in core 76 and preferably threadablymounted therein. A coil compression spring 83 is provided withinactuating sleeve 82 on contact actuating rod 44 and is adapted to reactbetween a shoulder in the core and a pin 84 extending transverselythrough actuating rod 44. A bushing 85 surmounts the sleeve 82 and isprovided with a ange Se'.

The circuit through the circuit breaker thus far described may now betraced from the point where it enters tank 2 through one of a pair ofterminal bushings 96 (only one being shown), each being provided with aconductor element which extends through the bushing seated in an openingprovided in the top wall of cover casting 6, andv proceeds by conductor98 directly to one fixed contact 26 of the breaker. When the contactsare in engagement, the circuit then proceeds through bridging contact 36to the other fixed contact 38, and then by way of a conductor 166 to oneterminal of solenoid coil 24.

' The other terminal of coil 24 is adapted to be connected by aconductor 102 to the conducting means in the other terminal bushing 90.It will be apparent that solenoid coil 24 in this embodiment of theinvention is connected in series in the circuit through the circuitbreaker so as to be energized at all times when the circuit breaker isclosed, an amount dependent upon the value of current owing in thecircuit.

For any given rating of circuit breaker, solenoid coil Y 24 is designedto become sufficiently energized when the load current in the circuitexceeds its rating sufficiently to attract core 76 and move it upwardlywithin sleeve 74. Core 76 will move upwardly relatively rapidly if thepassage 80 is open, and slowly if it is closed, since it is necessary todisplace the liduid in sleeve 74 above the core either through theopening 8l or through relatively small clearance between the core andsleeve '74. Accordincly if the opening 81 is open, as shown, opening fmovement of the core will not be slowed up appreciably V`by theaforesaid dashnot action, and opening movement thereof maybe relativelyranid. When core 76 commences its upward travel. bridging contact 36being engaged by toggle spring 63 does not move, so that spring .83 iscompressed until it is substantially solid, at which point the upper endof bushing 85 strikes a collar 87 n secured torcd 44. Thereupon,actuating rod 44 moves l overcome the closing bias of toggle spring 63,preferably at some point during initial movement of core '76 beforebushing SS engages collar 87 on actuating rod 44. However, collar 87 isprovided to obtain a positive contact separation in the event there isany sticking or welding of the bridging contact to stationary contacts26. In either case, it is apparent that toggle levers 52 and 54 will bemoved to their on-center position in the manner previously described,and bridging contact 36 will be moved by spring 83. When the breakercontacts have attained their full open circuit position, the partsassociated therewith are'biased to return by gravity.

In order to -limit the number of operations of the circuit breaker inclose succession upon the occurrence of a continuing overload on thecircuit, and to provide for manual operation, meansare provided forholding the reaker contacts open in response to the occurrence of apredetermined number of closely succeeding circuit interruptingoperations, which means can be manually actuated. This means comprises atoggle lever 104 pivoted at one end as at 196 on a U-shaped spring lever108 which, in turn is pivotally Supported as at 11% between the legs ofa U-shaped supporting bracket 111 secured to cover casting 5. The otherend of toggle lever 164 is pivoted, as by a pivot pin 112, to theadjacent end of a second toggle lever 114, and this, in turn, is mountedon a pivot pin 116 intermediate its ends, with the pin 116 being mountedin a bracket 118 secured to the adjacent wall of cover casting 6. A slot120 is provided through the cover casting 6 for receiving the other endof toggle lever 114, which acts as a manual operating handle at theexterior of the circuit breaker casing, being provided with an angledhook end 122. A coil compression spring 124 is mounted to react betweenthe bight of lever 168 and cover casting 6. Normally, toggle levers M34and 114 are held by spring 124 with pivot 112 below the center lineconnecting pins 106 and 116, with the outer end of lever 114 positionedin and beneath an integral hood 126 on cover casting 6, in engagementwith an adjustable stop screw 128 mounted in the hood.

In the position of toggle levers 104 and 114 illustrated, they have noeect on operation of the circuit breaker as previously described, beingnormally inactive in this respect. However, lever Hi8 has a connectingpin 113 extending beneath toggle levers S2 and 54. Accordingly, if it isdesired to manually open the circuit breaker contacts, a hook stick orsimilar operating member may be engaged with the upper side of anglehook 122 of toggle lever 114 and pulled downwardly to rotate the togglelever in a counter-clockwise direction about its supporting pivot 116 tomove toggle levers 104 and 114 overcenter in an upward direction, and indoing this, pin 113 engages toggle levers S2 and 54 and moves themupwardly in a counterclockwise direction, thus carrying contactactuating rod 44 upwardly to separate bridging contacts 3S fromstationary contacts 26. The contacts will be held open by spring 124,which maintains toggle levers 104 and 114 in their upper over-centerposition.

In thus manually opening the circuit, after toggle spring 68 is moved toits on-center position, it will be observed ythat the spring 124 is onlyrequired to maintain the contacts of the breaker open against therelatively light closing bias duc to gravity, and such light bias as maybe due to toggle spring 68 in the event that toggle levers 52 and 54 arestopped just prior to reaching their on-center position. With thebreaker contacts maintained at their open circuit position following themanual circuit opening operation described above, it will beapparent'that the outer end of toggle lever 114 projects below hood 126of cover casting 6 so as to provide a readily visible indication thatthe breaker contacts are maintained at open circuit position. It willfurther be apparent that the breaker contacts may then be closed only bymanual operation of toggle lever 114 in the opposite direction, that is,by exerting an upward force on the outer end ot the toggle lever byengagement of a hook stick or the like with the underside of hook 122,Vto rotate lever 114 in a clockwise direction to move it and toggle lever1434 back over-center to the full line position illustrated on thedrawings. An integrating mechanism is provided for automatically movingtoggle levers 104 and 114 upwardly over-center and thus preventingreclosure of the circuit breaker in response to a predetermined numberof closely successive circuit interrupting operations, comprising acylinl drical tube 130 clamped or otherwise secured in a lateralextension of casting 20 at the top of solenoid coil 24, and

l this tube has a plug 132 threaded into the lower end generally by thenumeral 16d. As best shown in Fig.. 2

trolled by a ball check valve 134, which permits ow of :iluidiiiitothelowerendof-t11be.130.but prevents outow. .Anfintegrating .piston-136.is.mounted in tube 130 .and ,normally restsonthe upper endof plug 132,being provided with a reduced extension 138 atthe upper end.thereofhaving a .plurality of spacedcircular flanges 140 forming rackteeth thereonVandfhaving an elongated ex- A.tension 142 of insulatingmaterial .on the extreme .outer endthereofwhich is positionedbelow anextension 143 ontoggle leverlld. A pawl lever144ispivotally mount- .edat one end asat 146, this end of .pawl lever being .split with legslocated at each side of tube 13@ and with .pivot 146 .supported onspaced supporting flanges 145 integral with casting 2l). Pawl lever 144has a conncctingweb intermediate its ends, and at the other end.t'hereofthesides .of theflever are extended outwardly and .laterally asat 148, to normally be in engagement with -ltlange.86.of.actuatingtube-82 adjacentthe outer end of thistube. Pawl lever 144 is normally biasedinto engagement with flange. 6 by a coil tension spring 152 hooked overthe remote edge of the web ofthe pawl lever at one end and anchored toan ear integral with casting 2i) at l.its other end. Pawl lever 144 isprovided with a pawl member pivoted thereon as at 156, and biased by aspring A158'in a counterclockwise direction to a position 'Awhereinaportion of pawl member 154 engages the connecting web of pawl-lever 144.

The tube 130 intersects the passage Sil of the dashpot,

and the piston y13rd acts as a valve to control venting thereof, so thatwith the piston as shown the dashpot .vents freely and. operation of thebreaker is rapid. When the piston 136 isrmoved upwardly by the pawl 154,it lirst partially and then completely blocks the passage Si) so as to-delay operation of the armature '76 slightly, and then withl an inversetime current characteristic.

In order to permit 'the breaker to be reclosed and handle the additionalload which accumulates due to loss of diversity of load after anextended outage, such as will occur when the breaker is reclosed afterhaving locked open for a relativeiy long time of, say, twenty minutes orlmore, recalibrating means may be provided, designated 'a resistor 161may be mounted adjacent coil 24, being, 'for example, secured to thelower plate 22 by a bolt 162 andinsulating spacer 163. An arm 165 may bepivotally nmounted,on plate 212 as by a pivot 166, having a contact forengaging a lixed contact 168 mounted on the upp'erfendof resistor 161and spaced therefrom by insulation 159.v AV spring 17d biases arm awayfrom casting 20.

The lower end of resistor y161 may be connected to the lower terminal ofcoil '24 by connector 171, while the upper Aend isconnected by allexible connector 172 to y,Contact 167. Connector 173 connects fixedcontact 168 .to the upper terminal of'coil 24, so that resistor 161 isconnected in shunt with coil 24 when the switch arm is actuated to theclosed position.

To actuate 165, a bellcrank 175 is pivotally mountedon projection 176 ofcasting 2), and connected to .toggle lever 114 link 177 and clevis 177(Fig. l), so as ,toi be operated to close switch arm 165 each time thetoggle relation of levers114, 104 is broken. A latch 178l having abimetallic actuating portion 179 is mounted on casting 2l) so as .to beactuated downwardly to a position to retain arm 165' in the closedposition, if the 'interruptor has been open for a1-predetermined time ofsay, abouttwenjty minutes or more, andH has cooled down sufficientlybelow thevnormal operating temperature, Ternerature'compensation may beelected by connecting a y ersely disposed bimetal element 186 (Fig. 1)positilo'ncd on `support rod 13 above the oil L to latch 173, as VVbyimkl 182, that changes in ambient temperature will not the operation ofthe latch.

" f lien' the circuit breakerop'e'rates to open Vthe circuit, :jflaglge`86` wi ll be carried upwardly with actuating sleeve 82 and thus carrythe free end of pawl lever 144 upwardly V.with it to .move pawlmember-,154 iuQ-.CngagementMith vbreaker remains closed, integratorpistonfldwillslowly reset to the position shown in Fig. l duetoleakageof lio id in cylinder Silbelow piston-136 through the relativelysmall clearance between the cylinder and piston.

vHowever, if the breaker immediately reopens after. .afirst opening andreclosing operation, pawl memberf154this time will engage the next lowercircular ilangei on. the integrator piston and raise the pistonafurther1 amount. Subsequent reclosing will resultA then .inleavingpiston 136 at this further advanced position from which .iteventually `will reset if the breaker remains closed. However, in theevent of a continuing overload, f-the breaker will again open andreclose, and the pawl.member 154 advances integrator piston 136an amountsufficient to cause theupper extension 142 thereof to engage .theextension 143 .of toggle lever 164 and move vthis lever upwardlyovercenter, so that toggle spring 124 will maintain the contactsseparated in the manner previously described. It is thus apparent thattoggle levers 104 and 11,4 will be automatically moved upwardlyover-center to maintain the breaker contacts separated, only inresponseto a predetermined number of closely successive circuitopeningand closing operations, usually four such operations. However, in theevent a lesser number of closely successive opening and closingoperations occurs, the integrating mechanism will reset and the breakercontactswill be automatically held open only when the aforesaidpredetermined number of opening and closing operationsoccurs in closesuccession. AObviously, after the breakercontacts have beenautomatically actuated toa position where they are held open by togglespring124, theyv can be reclosed only by manual operation of togglelever 114 in the. manner previously described.

When toggle levers 1 tl4rand3114are movedover-center, .link.177vactuates bellcrank lever 175 counterclockwiseto Vclose switch arm 165.Resistor 161 is thereby placed in shunt with coil 24 so as to requireagreater value of .current to effect a subsequent trip operation.

Should the recloser be reclosedshortlyafter such locking open,V andbefore the usual diversity of load is lost, the operating temperature ofthe recloser, which will run on the order of 25 to 30 degrees centigradeabovearnbient, will not have dropped ksufficiently for latch178 tobecome effective, and spring 170will open switch arm 165 as bellcrank17S is rotated clockwise by handle122. The interruptor will thereforehave its. normal trip rating.

Should the recloserremain open forabout twenty minutes or more, so thatthe usual diversity of load is. lost, the temperature of the recloserwilldrop as shown by ,curve (a) of 4, and latch 178 will be actuateddownwardly by bimeta 1W so as to be effective to latch. arm

closed. Thus when the recloser is reclosed,.switch arm 165 will remainclosed, and coil 24 will` be shunted by resistor 161, thus reducing `theeffective Yampere turns thereof. Accordingly, the trip current rating of-Athe recloser will be increased, as'shown by curve (b) of Fig.

3, and the recloser will beA able tohandle theincreased load current due.to loss of diversity. v

From .the l'above description and the accompanying drawings it willbeapparentthlat 1 have provided a reclosing circuit breaker withincreasedcold load pickup, Vwhich .means thatthe. normal trip currentmay be much closer to the normal rating, .while stillpernii'tting`greater yovercurrents to behandled ifthe breaker has been .open for.some time soas to permitloadtoaccumulate. v.ing fthe arm 165 of vavmagneticmat e rial,. ,the ,magnetic attraction between arm 165 andcasting 20 may be utilized to prevent interrupting excessively heavycurrents at the switch arm contacts, such as might occur should latch$.76

be released during an overload. Existing breakers may be readilymodified according to my invention with a minimum of labor and expense.

Having described a preferred embodiment of the invention in accordancewith the patent statutes, it is desired that this invention be notlimited to this particular construction inasmuch as it will be apparent,particularly to persons skilled in this art, that many modificationschanges may be made in this particular structure without departing fromthe broad spirit and scope of this invention. Accordingly, it is desiredthat the invention be interpreted as broadly as possible and that it belimited only as required by the prior art.

I claim as my invention:

1. A circuit interrupter comprising, separable contacts, an operatingmechanism therefore, electrorcsponsive means operable to actuate saidmechanism to eiect separation of said contacts, lockout means actuatedby a predetermined number of operations of the electroresponsive meansto maintain said contacts separated, switch means actuated by thelockout means operable to vary the etico tiveness of saidelectroresponsive means when the contacts are maintained separated, andreleasable means operable in accordance with a predetermined temperaturecondition of the interruptor to maintain said switch means operated.

2. In a circuit interrupter, separable contacts, an operating mechanismfor said contacts, a solenoid having an armature movable to actuate saidmechanism to separate the contacts in response to a predetermined valueof cur rent, lockout means operable to hold said contacts separated,switch means operable in response to said lockout means to decrease theeffective ampere turns of said solenoid, and releasable means forretaining said switch means operated when the temperature of theinterrupter is below a predetermined value.

3. A circuit interrupter comprising, separable contacts, an operatingmechanism for said contacts, electroresponu sive means having anarmature movable in response to a current above a predetermined value toactuate said operating mechanism to effect separation of said contacts,lockout means actuated by a predetermined number of closely consecutiveoperations of said electroresponsive means to maintain said contactsseparated, means operable to reduce the effectiveness ot theelectroresponsive means actuated by operation of the lockout means, andreleasable means operable in accordance with the temperature of theinterrupter for maintaining the aforesaid means operated it the contactsare maintained separated for more than a predetermined time;

4. In a circuit interrupter, separable contacts, an operating mechanismtherefor, electroresponsive means for actuating said mechanism to effectseparation of said conv tacts in response to an overcu rent, lockoutmeans actuated by a predetermined number of separations of said contactsoperable to maintain said contacts separated in response to apredetermined number of closely consecu tive separations, recalibratingmeans actuated by operation of said lockout means to recali'orate saidelectroresponsive means and increase the value of overcurrent Y requiredto operate the electroresponsive means, and latch means operable inresponse to said contacts remaining open for a predetermined time toretain the recaiibrating i means operative when the contacts are closed.

l of the electroresponsive means in response to overcurrent conditions,recalibrating Ymeans operated by the lockout means when it operates tomaintain said contacts separated to reduce the effectiveness of saidelectroresponsive means, biasing means for rendering the recalibratingmeans non-operative, and thermally responsive latch means for retainingthe recalibrating means operated after the temperature of theinterrupter reaches a predetermined minimum value.

6. in a circuit interruptor, separable contacts, an o'perating mechanismfor said contacts, electroresponsive means operable to actuate saidmechanism for separating said contacts, lockout means operated by apredetermined number of contact separations to maintain said contactsseparated, recalibrating means operated by the lockout means when itacts to maintain separation of said contacts to reduce the effectivenessof the electroresponsive means, biasing means normally making therecaiibrating means inoperative when the contacts are closed, andthermoresponsive releasable means operable to retain the recalibratingmeans operative against the effect of said biasing means when thetemperature of the interruptor reaches a value a predetermined amounbelow the operating level.

7. In a circuit interrupter, separable contacts, operating meanstherefor including a solenoid having a movable armature for separatingthe contacts, lockout means operated by closely successive contactseparations to maintain the contacts separated, switch means connectedin circuit relation with the solenoid operable to reduce the effectiveampere turns of the solenoid, actuating means operated by operation ofthe lockout means to eifect operation ot the switch means, biasing meansnormally' effective to open the switch means when said contacts areclosed, and releasable means maintaining the switch means operated whenthe contacts remain open for greater than a predetermined time.

S. A circuit interrupter comprising, separable contacts, operating meansfor said contacts, electroresponsive means for actuating said operatingmeans and separating said contacts including a solenoid having auarmature responsive to a predetermined value of current, lockout meansfor biasing the operating means and maintaining the contacts separated,a counter having a member advanced by closely successive operations ofthe electroresponsive means to effect operation of the lockout means toeventually lock said contacts open, an impedance device, means includinga switch actuated by the lockout means connecting the impedance devicein circuit relation with the solenoid, and releasable means operablewhen the ternL erature of the interruptor mls below a predeterminedtemperature to maintain said switch in the actuated position.

9. in a circuit interrupter, separable contacts, means including asolenoid having an armature for electing separation of said contacts,lockout means for maintaining said contacts open, a counter operated byclosely successive separations of said contacts to effect operation ofthe lockout means, a resistor, a switch, operating means operable inresponse to operation of the lockout means to eiiect operation of theswitch to connect the resistor in circuit with the solenoid to reducethe effective ampere turns of the solenoid, said switch being normallydisposed to open when the interrupter is closed, and a latch having abimetallic member for retaining the switch closed when the temperatureof the oil drops below a predetermined value while the interrupter isopen.

1G. A circuit interrupter comprising, separable contacts, operatingmechanism therefore, a solenoid having armature operable in response toa predetermined value of current to operate said mechanism to separatesaid contacts, said contacts being biased to reclose, lockout meansoperable to maintain said contacts separated against the reclosing bias,a counter operable in response to closely successive operations of thearmature to effect operation of the lockout means, a resistor, a switchactuated by operation of' the counter to connect ythe re sistor in shuntwith'at least a portion of the solenoid,

and latch means including a temperature responsive member retaining saidswitch closed, only if the interrupter remains open for sufficient timefor the temperature thereof to fall below a predetermined level.

ll. A circuit interrupter comprising, separable contacts, an operatingmechanism for said contacts, electroresponsive means for operating saidmechanism and separating said contacts in response to a current above apredetermined value, a lockout mechanism for locking said contacts open,a counter operated by a predetermined number of closely successiveoperations of the electroresponsive means, a switch actuated by thelockout mechanism to reduce the effectiveness of the electroresponsivemeans, and a bimetallic latch for engaging a portion of the switch andretaining the switch actuated when the contacts are closed, provided thetemperature of the interrupter has ldropped below a predetermined value.

l2. In a circuit interrupter, separable contacts, an operating mechanismfor said contacts, electroresponsive means including a solenoid havingan armature for opterating said mechanism and etecting separation ofsaid contacts, lockout means for maintaining said contacts separated, acounter actuated by a plurality of contact yseparations to effectoperation of the lockout means, a resistor, a switch actuated by thelockout means to connect the resistor in shunt with at least a portionof the solenoid, a bimetallic latch element for engaging a portion ofand retaining the switch closed if the temperature of the interrupter isbelow a predetermined value, and a bimetallic element opposing saidlatch element compensate for changes in ambient temperature` l3. In acircuit interrupter, separable contacts, means including a solenoidhaving an armature movable to eiTect Separation of said contacts, amagnetic circuit for said solenoid including pole pieces of magneticmaterial, lockout means for maintaining said contacts separated, acounter operated by a predetermined number of closely successiveseparations to eifect operation of the lockout means, means shuntingsaid solenoid including a switch having an armature of magnetic materialextending between said pole pieces so as to be held closed for eX-cessive currents by magnetic attraction to at least one of the polepieces, actuating means for closing said switch only when the lockoutmeans operates, and latch means including a bimetallic element forholding the switch closed so iong as the temperature is below apredetermined level.

lfi.. A circuit interrupter comprising, a container having insulatingoil therein, a cover for said container, separable contacts supported insaid oil from said cover, means for separating said contacts including asolenoid supported from the cover in said container responsive tocurrent above a predetermined value, means biasing said contact-sclosed, lockout means operable to maintain said contacts separated, acounter actuated by closely successive separations ot" the contacts foroperating the lockout means to maintain said contacts separated after apredetermined number of such operations, a. resistor, a switchconnecting the resistor in shunt with the solenoid, actuating means forsaid switch operated by the lockout means, a spring biasing the switchopen, and a latch having a bimetallic operating member mounted adjacentthe solenoid disposed to engage and latch the switch closed when thetemperature of the solenoid and oil falls a predetermined amount below anormal operating temperature.

References Cited in the tile of this patent UNITED STATES PATENTS2,274,135 Frank et al Feb. 24, i942 2,349,632 May May 23, 1944 2,361,221Ludwig et al. Oct. 24, 1944 2,468,498 Kyle et al Apr. 26, 1949 2,468,851Wallace May 3, i949 2,655,575 Wallace et al. Oct. 13, 1953

